If Trump imposes 25% tariffs on Chinese goods, China could simply devalue their currency by 25%. That would make Chinese goods cheaper for U.S. buyers by the same amount as the tariff. The net effect on price would be unchanged and Americans could keep buying Chinese goods at the same price in dollars.
The impact of such a massive devaluation would not be limited to the trade war. A cheaper yuan exports deflation from China to the U.S. and makes it harder for the Fed to meet its inflation target. Also, the last two times China tried to devalue its currency, August 2015 and December 2015, U.S. stock markets crashed by over 11% in a matter of a few weeks. So, if the trade war escalates as I expect, don’t worry about China dumping Treasuries or imposing tariffs.